This invention relates to trench shoring assemblies and, in particular, to trench shoring assemblies known as trench boxes.
Trench boxes are used in excavation work when pipe or conduit is being laid. Basically, a trench box comprises two side walls which are spaced apart a fixed distance from each other by a plurality of spreader devices affixed to and perpendicular to each side wall. The assembled trench box is positioned in an excavation hole or trench and pipe is laid within the trench box, and after each length of pipe is laid the trench box is moved along the trench for laying the next length of pipe. The side walls of the trench box keep the excavation area about the laid pipes free from earth which may fall or cave into the excavated hole or trench during or before the laying of the pipe.
It is frequently necessary to pound the side walls of a trench box into the ground of the excavated trench to firmly position the trench box. A wooden plank has been positioned on the top of the side wall before pounding forces are applied to drive the side wall into the ground, however, the wood splinters and the wooden plank is useless within a short time. In addition, the top structural member which extends longitudinally along the top of the side wall becomes deformed as a result of the pounding forces, resulting in very little force being transferred to the remaining frame members of the side wall and damage to the assembly.
In accordance with the present invention there is provided a trench shoring assembly including a pair of interconnected spaced wall means defined by interconnected structural members including a hollow structural member extending longitudinally along the top of the wall means with force transferring means disposed within the hollow structural member for preventing the collapse of the hollow structural member as the top of the wall means is pounded.
The present invention reduces the distortion and bulging of the top frame members by positioning a force transferring means such as a hardwood insert within a hollow top structural member to prevent the collapse of the hollow structural member. The hollow structural member is interconnected to a plurality of metal beams which are part of the structural members of the side wall whereby the pounding forces applied to the hollow structural top member are transferred to the metal beams of the side walls.